Skin Cooling Linked to Post-Laser Treatment Discoloration
Hori nevus patients nearly three times as likely to develop hyperpigmentation on cooled side of face
FRIDAY, Sept. 21 (HealthDay News) -- In patients with acquired bilateral nevus of Ota-like macules, laser treatment accompanied by cold-air cooling may increase the risk of post-inflammatory hyperpigmentation, according to a report published in the September issue of the Archives of Dermatology.
Woraphong Manuskiatti, M.D., of Mahidol University in Bangkok, Thailand, and colleagues treated 23 Thai women with a 1,064-nanometer Q-switched Nd:YAG laser. They randomly selected one side of each patient's face to receive 30 seconds of cold-air cooling before and after irradiation and the other side to receive irradiation without cooling. Twenty-one patients completed the study.
The researchers found that hyperpigmentation was significantly more likely to occur on the cooled than the uncooled side (relative risk, 2.6). Thirteen patients developed hyperpigmentation on the cool side compared to five who developed it on the uncooled side. One patient developed it on both sides, and two did not develop it at all. Almost two-thirds of hyperpigmentation cases developed within two weeks after treatment, but all the cases except one completely resolved within 12 weeks after treatment.
"The mechanism by which cold-air cooling is associated with an increased risk of post-inflammatory hyperpigmentation after laser treatment is unknown," the authors conclude. "It is possible that the mechanism was a melanocyte's or keratinocyte's responses to the laser pulses together with cold-air exposure."